There, they provoke inflammation and trigger immune responses — including overactivation of CD8+ T cells, immune cells that normally destroy infected or abnormal cells. When these cells go into overdrive, they worsen liver damage.

The takeaway: a disease centered in the liver can be driven by events in the gut.

What did the drug actually do?

In both mice and nonhuman primates, DT-109 cut levels of Clostridium perfringens and reduced ammonia production in the intestines. That strengthened the intestinal lining and limited how many harmful microbial substances reached the liver.

The primate results matter most. Monkey liver biology and gut microbial communities resemble humans far more closely than mouse biology does. In these animals, DT-109 reduced liver inflammation and lessened MASH severity.

"DT-109 connects microbiota modulation with liver protection by restoring gut barrier integrity and limiting the systemic translocation of ammonia and other pro-inflammatory microbial products within the gut-liver axis," said Jifeng Zhang, Ph.D., co-author and research professor of cardiovascular medicine at U-M Medical School.

The gut-liver axis is the tight biological link between the digestive tract and the liver. Substances absorbed in the intestines flow straight to the liver through the bloodstream, which makes liver health unusually sensitive to gut conditions.

"We also found that DT-109 primarily acts in the gastrointestinal tract, but its reach stretches much further," Zhang said.

In short: the drug works in the gut, and the liver benefits.

Could it help beyond the liver?

Possibly. Earlier research showed DT-109 can reduce atherosclerotic plaques — fatty deposits that build up inside artery walls — and prevent vascular calcification, the hardening of blood vessels from calcium buildup, in nonhuman primates.

The researchers also want to know whether it could help people with inflammatory bowel disease, a group of chronic conditions that includes Crohn's disease and ulcerative colitis. A treatment that strengthens the intestinal barrier might have benefits beyond the liver.

That's speculation for now. Additional research will be needed before anyone can say whether DT-109 works against those conditions.

What's the catch?

A big one: no human data yet. DT-109 has reversed MASH only in animal models, and researchers haven't established whether it's safe and effective in people. The next phase aims to move the compound toward clinical trials, which will test safety, dosing, and real-world effectiveness.

"This study presents novel evidence about the pathogenesis of MASH and provides excitement about a therapeutic avenue to explore for a condition that remains difficult to treat," said Elliot Tapper, M.D., Academic Director of Hepatology at Michigan Medicine.

"What patients with MASH need is a safe and effective therapy capable of improving their liver and heart health — of course we are excited about these developments," Tapper said.

There are financial ties to disclose. Chen, Zhang, and colleagues are listed as inventors on a patent application covering tripeptides for metabolic, cardiovascular, and inflammatory disorders. Chen is an inventor of DT-109 itself. The University of Michigan holds the patent, has licensed it to Diapin Therapeutics, and — along with Chen — holds an ownership stake in the company, which supplied the drug for the research and is developing it further.

Bottom line: if human trials confirm the animal results, a drug that heals the gut could become a new option for millions of people with severe fatty liver disease — and possibly their hearts too.